Almost all microscopes that you get in the Rs. 10K-50K are brightfield microscopes. The background (=field) is white (=bright). The object that you see (f.e. a cell) is stained so that it stands out clearly against this bright background. Stains are basically special chemicals that attach to specific things in the object and impart colour to it. F.e. in a plant cell Safranin O (a stain) gives red colour to nuclei, Fast Green gives green colour to cell wall. This way the structure of a cell is distinctive to see under a microscope. If not stained, the cells look kind of greyish and artefacts are fuzzy and blend into the background.
Attach a dark field stop to the condenser of a brightfield microscope, you get a darkfield microscope. Well, sort of. Actual darkfields are little more than this.
Remove the brightfield condenser and standard objectives, and attach a phase contrast condenser and phase objectives, you get a phase contrast microscope.
So to sum up, all microscopes, unless specified otherwise, are brightfield by default.
Now about the quality standards...
UL is a quality certification of the electronics/electrical part of the microscope (or any other item, for that matter). Very broadly speaking, it kinda assures you that the product is electrically safe
ISO is a quality
management system. It helps you manage/attain some quality. What that quality is, is up to you. For example, a company fabricates certain lengths of iron rods from longer rods. It has automated cutting machines that can cut accurately with a tolerance of +/- 0.1mm length. But the boss decides to cut lengths with accuracy of 1mm, and also claims +/- 1mm error to his customers. So a 100mm rod from this company could be anywhere between 99-101mm. Another company with same machines, says its rods have an error of +/-0.1mm but actually produces rods that have an error of +/- 0.5mm. So this company claims to sells 100mm rods that are supposed to be 99.9-100.1mm long, but actually could be between 99.5-100.5mm. Which company do you think has better quality?.. The first company, coz it gives what it says. But I digress... Very broadly speaking, ISO (ISO 9001 relevant for manufacturing/selling) will document what you do and how you do it; basically your functions, processes, products, systems, designs etc. Its not a validation of the end product, just the processes that go into producing the end-product. Intrinsic in this is if the processes etc. are quality controlled, the product will be too... Once again, ISO is NOT an end-product quality certificate.
For product quality, you should be looking at the ISI mark. But you know how things are in India. A few years back, I was told that the going rate for Ambala microscopes to be ISI certified is Rs. 50. Even a shitty microscope + Rs. 50, and you can have it ISI marked. So basically quality certificates and assurances are not worth the paper they are printed on.
There's a reason optical things are so expensive. Be it camera lenses, telescopes, microscopes. Good ones are really difficult to produce and demand a certain setup of infrastructure, technology, knowledge and personnel that are seriously costly.
If you are going for a low cost microscope, a binocular for Rs. 12K won't be much better than one that is Rs. 8K. You'll find a lot of these in Princess Street.
If you do decide to increase your budget my suggestions once again are: Labomed CxL (~Rs. 28K) -> Olympus CH20i (Rs 39K) -> Olympus CX21i (Rs. 50K).
Regards,
Mohit.
www.BioZen.co.in
; to the realms of the cosmos.
and I concede - unlike making so many difficult choices in life [like chosing an i7-3920XM vs 3770K vs 3570 or GPU's where the performance is acceptable based on your needs] - chosing a microscope (& telescope) is the hardest.
